[jonc2006]

try naming the .bat file "autoexec.bat". i have several games where i have had to do this in order for my custom settings to override the defaults.

edit- you could also try adding that same command switch to the config file for dx or the config file for the game itself. another method might be creating a config file called "autoexec" in the same directory that has the game config file and put the switch into there.